There are people who believe that Harry Potter condones the occult and satanism, etc. It doesn't matter what JK Rowling's intentions might truly be. It doesn't matter that she has simply chosen to write something that is truly magical, fun, and imaginative and innocent.
Anne Rice could have written a vampire novel like many of the others---where Dracula engages in a "love affair" with women only. Instead, she chose to obey the notion that vampires can not have sex, but infuse her novels with very pro gay/bi erotic love.
And just because you are reading too much into it, doesn't change what she created or tried to create. And I seriously doubt that when heterosexuals who are not experienced in gay culture or gay anything read her books or see two men being sensual in a film or musical of her books, they will walk away feeling that what they saw was anti-gay.
I just don't think you have a valid argument--and just like with art2's inane attacks on the Rent trailers, I think this is a ludricrous thing to get worked up about when there are so many other actual horrific things happening to gays and lesbians in the media and in politics and in society to fight against. Things that are DEFINITELY anti-gay or that DEFINITELY encourage negative stereotypes than a musical (Created by gays and gay friendly people) that MIGHT put across subliminal mistaken anti-gay thoughts.